Diaphragm and labyrinth seal assembly for gas turbines

ABSTRACT

The diaphragm member and labyrinth seal assembly for a gas turbine machine comprises an annular diaphragm or wall member disposed adjacent at least one of the rotor discs of a rotor blade assembly to define with the rotor disc a cooling fluid chamber. The chamber is in communication with a source of cooling fluid such as air, to receive cooling fluid from the latter. A labyrinth seal is disposed between the rotor blade assembly and the diaphragm member to provide a relatively fluid-tight joint between the stationary diaphragm member and the rotating rotor blade assembly. A slipjoint connecting means is disposed to connect together the diaphragm member to the turbine housing, which connecting means maintains concentricity of the diaphragm member and turbine housing and permits thermal differential movement of the diaphragm member and turbine housing without affecting the efficiency of the labyrinth seal.

United States Patent [191 DeFeo DIAPHRAGM AND LABYRINTH SEAL ASSEMBLY FOR GAS TURBINES [75] Inventor: Angelo DeFeo, Passaic, NJ. [73] Assignee: Curtiss-Wright Corporation,

Wood-Ridge, NJ. [22] Filed: July 30, 1973 [21] App]. No: 383,576

[52] US. Cl 415/136, 415/172, 415/117 [51] Int. Cl. F0ld 25/24, FOld 25/26, F02d 7/20 [58] Field of Search 415/136, 134, 138, 139, 415/172, 173, 117; 60/3932 [56] References Cited UNITED STATES PATENTS 2,488,867 11/1949 Judson 415/136 2,903,237 /1959 Petrie et al. 415/138 2,919,891 1/1960 Oliver 415/136 3,376,017 4/1968 Rizk et al 415/138 3,759,038 9/1973 Scalzo et al 415/134 Primary ExaminerCarlton R. Croyle Assistant Examiner-Louis J. Casaregola Attorney, Agent, or FirmArthur L. Frederick July 16, 1974 5 7 ABSTRACT The diaphragm member and labyrinth seal assembly for a gas turbine machine comprises an annular diaphragm or wall member disposed adjacent at least one of the rotor discs of a rotor blade assembly to define with the rotor disc a cooling fluid chamber. The chamber is in communication with a source of cooling fluid such as air, to receive cooling fluid from the latter. A

.3 .C'si na?P ewlr iisqqi //6 I 26 Z 2d f g //0 w #02 a?" #2 42/ a a MA f--| a 18 l 32 y If 7.? 1 Z [a J PATENTED JUL 1 s 1974 saw 2 ur a PATH-HEB JUL! 6 2314 I saw 3 or 4 DIAPHRAGM AND LABYRINTH SEAL ASSEMBLY FOR GAS TURBINES DISCLOSURE OF INVENTION This invention relates to fluid elastic machines, such as gas turbines, and more particularly to the diaphragm means and labyrinth seal assembly disposed adjacent to the rotor discs of gas turbine machines.

BACKGROUND OF THE INVENTION In gas turbines having a plurality of rotors it is essential for relatively long, trouble-free operative life to provide means for cooling the rotor discs or hubs of the turbine. Conventionally, this rotor disc cooling has been achieved by providing wall means, partition means or diaphragm means cooperating with the housing means, including stator vane assemblies, to form chambers adjacent the rotor discs into which chambers cooling fluid such as air, is introduced. To render the chambers reasonably fluid-tight, a labyrinth seal is conventionally provided between the diaphragm means and rotor discs, one part of each of the labyrinth seals being carried by a diaphragm means while the other part is carried by a rotor disc. It has been found that in such installations the integrity or efficiency of the labyrinth seals cannot be maintained because of the differential, radially directed, expansion and contraction between the turbine housingand the stator vanes which, in turn, through the diaphragm means causes one part of the labyrinth seal to move relative to the other part.

Accordingly, it is an object of the present invention to provide in a gas turbine a diaphragm means and labyrinth seal assembly wherein integrity of the labyrinth seal is unaffected by differential thermal expansion and contraction of the turbine components.

Another object of this invention is to provide in a gas turbine a diaphragm means and labyrinth seal assembly wherein efficiency of the labyrinth seal is independent of the relative expansion and contraction of the stator vanes and turbine housing.

A further object of the present invention is to provide in a gas turbine a diaphragm means and labyrinth seal assembly wherein concentricity of the labyrinth sea] component parts is maintained during all phases of turbine operation.

A still further object of this invention is to provide in a gas turbine a diaphragm and labyrinth seal assembly which permits the selection of the material for the inlet housing and the diaphragm without regard to their respective thermal coefficients.

A feature of this invention is the expansion joint interconnection between a diaphragm means and housing means, including stator vane assembly, which permits relative radial movement between the associated diaphragm means and housing means upon differential expansion and contraction of those components. This allowance for relative movement between the diaphragm means and housing means prevents relative radial movement of the component parts of the associated labyrinth seal, thus permitting the component parts of each of the labyrinth seals to maintain desired predetermined clearances.

SUMMARY OF THE INVENTION Accordingly, the present invention contemplates, in

a gas turbine machine having at least one stator vane assembly and one rotor blade assembly disposed within a housing means, a diaphragm means and labyrinth seal assembly comprising a stationary annular partition means or diaphragm means disposed adjacent the rotor disc of the rotor blade assembly to define with the latter a cooling fluid chamber which is in communication with a suitable source of cooling fluid, such as air. A labyrinth seal is disposed between the rotor blade assembly and the diaphragm means to provide a substantially fluid-tight joint between stationary diaphragm means and the rotating rotor blade assembly. The labyrinth seal is constructed and arranged to provide for a controlled amount of fluid leakage for the passage of cooling fluid therethrough. The diaphragm means is connected to the housing means via a slipjoint connecting means which permits radially directed differential thermal expansion and contraction between the diaphragm means and the housing means. This slipjoint connecting means provides in the assembly of the turbine the flexibility which may be necessary to obtain the desired labyrinth seal clearances without introducing thermal stresses into the assembly. The slipjoint connecting means also permits the maintenance of the desired clearances between the component parts of the labyrinth seal even under the effects of differential thermal expansion and contraction of the housing means relative to the diaphragm means.

In a more specific aspect of this invention the slipjoint connecting means comprises meshing radially extending splines constructed and arranged to allow relative movement in a radial direction but preventing relative rotative movement.

In a further specific aspect of this invention the slipjoint connecting means constitutes meshing radially extending splines between the inner inlet shell and the first stage stator vane assembly and between the outer inlet shell and the first stage stator vane assembly so that the annular inlet assembly is permitted to move relative to the first stage stator vane assembly and the diaphragm means.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following description when considered in connection with the accompanying drawings in which:

FIG. 1 is a schematic view in longitudinal crosssection of a gas turbine having a diaphragm and labyrinth seal assembly according to this invention;

FIG. 2 is a fragmentary view in longitudinal crsssection of the gas turbine shown in FIG. 1;

FIG. 3 is an enlarged fragmentary view in longitudinal cross-section, similar to FIG. 2 but on a much larger scale; and

FIGS. 4, 5 and 6 are each fragmentary cross-sectional views taken substantially along lines 4-4, 5-5 and 6-6 of FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Now referring to the drawings, and more particularly to FIG. 1, the reference number 10 designates a gas turbine which may form part of a power generating apparatus wherein a combustion gas generator, such as a turbojet engine (not shown), is connected, through an inlet passageway 12, to gas turbine 10 to deliver combustion gases to the latter. The combustion gases flowing into gas turbine are conventionally at an elevated temperature, as for example in the range of about 1,200 F to about 1,450 F. The combustion gases after expansion in gas turbine 10 discharge into an annular outlet passageway 14 and thence into an outlet volute section 16. From the outlet volute section 16, the exhaust gases pass to atmosphere via a stack 18.

As best shown in FIGS. 2 and 3, gas turbine 10 comprises an annular housing structure to which is connected in any suitable manner well known in the art, a first-stage stator vane assembly 22 and a second-stage stator vane assembly 24. Disposed adjacent stator vane assemblies 22 and 24 are a first-stage rotor blade assembly 26 and second-stage rotor blade assembly 28. Each of the rotor blade assemblies 26 and 28 comprises a plurality of circumferentially arranged blades 30 supported in a hub or disc 32. Each of the stator vane assemblies 22 and 24 comprises a plurality of circumferentially spaced vanes 33. The hub or discs 32 of each of the rotor blade assemblies 26 and 28 are connected together and to a driveshaft 34 for conjoined rotation by a plurality of circumferentially spaced tie-bolts 36.

The driveshaft 34 is connected to drive another device (not shown), such as an electrical generator. A partition, wall or diaphragm 38 is disposed adjacent to and spaced from the first-stage rotor blade assembly 26. The periphery of diaphragm 38 is connected to the inner wall 40 of inlet passageway 12, by a slipjoint connection 42, hereinafter more fully explained. Another partition wall or interstage diaphragm 44 is disposed between the first and second-stage rotor blade assemblies 26 and 28. To provide relatively fluid-tight annular chambers 46 and 48 on opposite sides of disc 32 of first-stage rotor blade assembly 26, labyrinth seal assemblies S0 and 52 are provided between diaphragms 38 and 44 and rotor discs 32 while, at the outer peripheral portion of rotor disc 32 of rotor blade assembly 26, running seals 54 and 56 are provided.

As best shown in FIG. 3, labyrinth seal assembly 50 of conventional construction comprises an annular ring 58 which is mounted on disc 32 of first-stage rotor blade assembly 26 and a shroud 60 secured to and forming part of diaphragm 38. The ring 58 is provided with a plurality of spaced annular ribs 62 which are in a predetermined juxtapositional relationship with spaced annular ribs 64 mounted on shroud 60 to provide for a predetermined fluid leakage into chamber 46. This fluid leakage flow path provides the means, as hereinafter more fully described, for introducing cooling fluid into chamber 46.

The labyrinth seal assembly 52 which also may be of well known construction, comprises a first annular ring 66 mounted between and secured to discs 32 of the first and second-stage rotor blade assemblies 26 and 28 and a second annular ring 68 secured to diaphragm 44 in concentric relationship to ring 66. Each of the rings 66 and 68 have a plurality of annular, spaced ribs, 70 and 72, respectively, which are in a predetermined juxtapositional relationship to each other to provide for a predetermined amount of fluid leakage into the annular space 73 between diaphragm 44 and disc 32 of secondstage rotor blade assembly 28.

As illustrated only in FIG. 2, to effect cooling of discs 32, cooling fluid, such as air at a temperature in the range of about 400 to 680 F, is supplied to cooling chambers 46 and 48 and annular space 73 by a supply duct 74 which is connected, at one end, to a suitable source of cooling fluid (not shown) and, at the opposite end, to diaphragm 38. As best shown in FIG. 3, one portion of the cooling fluid flows past shroud 60, through labyrinth assembly 50, into chamber 46, while another portion of the cooling fluid passes through central bore 75 in disc 32 and thereafter, through a plurality of radially extending openings or ports 76 in ring 66, into chamber 48. Also part of the cooling fluid entering chamber 48 passes into annular space 73, through labyrinth seal assembly 52, to effect cooling of the forward face of disc 32 of rotor blade assembly 28.

In accordance with this invention and as best shown in FIGS. 3 and 4, the integrity of labyrinth seal assembly 52 is preserved against the differential thermal expansion and contraction of housing structure 20, in-

cluding stator vane assembly 24, and the interstage diaphragm 44 by a slipjoint connection 78 between the roots 82 of the stator vanes and diaphragm 44. As best illustrated in H6. 4, diaphragm 44 is provided with a plurality of radially extending splines which mesh with radially extending, circumferentially spaced roots 8-2 which cooperate to form splines. The radial clearances at 84 between the splines 80 and root splines 82 permits relative radial movement between stator vane assembly 24 and diaphragm 44, thus preventing relative movement between rings 66 and 68 of labyrinth seal assembly 52. Since the predetermined clearances between ribs 70 and 72 of rings 66 and 68 are maintained despite the differential thermal expansion and contraction of the turbine housing structure 20, including stator vane assembly 24, and diaphragm 44, the sealing efficiency of the labyrinth seal assembly 52 is preserved. Also, the meshing splines 80 and root splines 82 of slipjoint connection 78 coact to maintain the angular relative position of the stator vane assembly 24 and interstage diaphragm 44 about the longitudinal axis of turbine 10 to further insure the maintenance of the sealing efficiency of labyrinth seal assembly 52.

To prevent relative linear movement of stator vane assembly 24 and interstage diaphragm 44 which movement, if it occurred, would adversely effect the integrity of labyrinth seal assembly 52, meshing splines 80 and 82 are held in axial alignment between an annular flange 85 of seal 56 and a washer or ring 86 (see FIG. 3). A plurality of circumferentially spaced bolts 88 clamp flange 85 and ring 86 against the opposite sides of splines 80 and 82 sufficiently tight to prevent longitudinal linear movement, but not sufficient to prevent, under differential thermal expansion and contraction, relative radial movement of the splines.

Similar to slipjoint 78, the vanes 33 of stator vane assembly 22 and diaphragm 38 are interconnected so that relative radial movement is permitted between the roots 90 of the stator vanes and diaphragm 38. This is accomplished by a ring 96 which is secured by a plurality of circumferential bolts 98 to a reversed L" shaped end portion 100 of diaphragm 38 (see FIG. 3), these elements defining receptacles for roots 90 of the stator vanes. As shown in FIGS. 3 and 5, ring 96 also forms part of slipjoint 42 by which relative radial movement between inner wall 40 of inlet passageway 12 and diaphragm 38 can occur and concentricity can be simultaneously maintained. In addition to ring 96 which has, as best shown in FIGS. 3 and 5, axially extending splines 102, slipjoint 42, comprises a washer or ring 104 which has splines 106 constructed and arranged to mesh with splines 102. The ring 104 is secured to a flanged end portion 108 of wall 40 by a plurality of bolts 110. Furthermore, the longitudinal clearances at 112 between meshing splines 102 and 106 permits relative longitudinal thermal expansion and contraction between wall 40, as well as radial movement of the stator vane assembly 22 relative to diaphragm 38, and thereby prevents movement of diaphragm 38, which movement would adversely affect labyrinth seal assembly 50.

As best shown in FIGS. 3 and 6, another slipjoint 114, similar to slipjoint 42, is provided to connect the outer wall 116 of inlet passageway 12 to housing structure 20. This slipjoint 114 comprises radially extending meshing splines 118 and 120 which, while permitting relative radial movement between the wall 116 and housing structure 20, prevents relative rotative movement between the parts. As shown, relative longitudinal movement between wall 116 and housing structure is prevented by a ring 122 which is secured by a plurality of bolts 124 against the splines. The ring 122 is press-fitted within the annular flange 126 of the housing structure 20.

It is believed now readily apparent that the present invention provides a diaphragm and labyrinth seal assembly for a gas turbine in which the effectiveness of the labyrinth seal is unaffected by the radial expansion and contraction of the housing structure, including the stator vane assemblies connected thereto, relative to diaphragms which define with the discs of the rotor blade assemblies cooling fluid chambers for cooling the discs. It is a diaphragm and labyrinth seal assembly which maintains its angular position relative to the turbine housing structure about the longitudinal axis of the gas turbine. This isolation of the labyrinth seal from the effects of radial relative movement due to differential expansion and contraction of the diaphragm and housing structure and the assurance of continued concentricity enables the predetermined clearance between the ribs of the labyrinth seal to be maintained and hence the sealing efficiency and cooling fluid distribution preserved.

Although but one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention, as the same will now be understood by those skilled in the art.

What is claimed is:

1. In a gas turbine machine having at least one stator vane assembly and one rotor blade assembly, including a rotor disc, disposed within a housing and an inner wall spaced inwardly from the housing to define with the latter an inlet passageway for conducting combustion gases to said stator vane assembly, an improved diaphragm and labyrinth seal assembly comprising:

a. a diaphragm means disposed adjacent to the rotor disc of said rotor blade assembly to define with the rotor disc a cooling fluid chamber;

b. each vane of stator vane assembly having a root portion;

c. a first slipjoint connecting means for connecting said root portions of said stator vanes to the diaphragm means so that relative radial movement is permitted between the stator vanes and diaphragm means due to thermal differential expansion and contraction;

d. a source of cooling fluid in communication with the fluid chamber to provide the latter with cooling fluid;

e. a labyrinth seal disposed between the diaphragm means and the rotor blade assembly;

f. one part of said labyrinth seal being carried by diaphragm means while another part is carried by the rotor blade assembly; and

g. a second slipjoint connecting means for connecting the diaphragm means to the inner wall of the inlet passageway so that thermal differential expansion and contraction in a radial direction is permitted between the inner wall and said diaphragm means;

h. said first and second slipjoint connecting means coacting to permit relative radial movement between the diaphragm means and said inner wall and stator vanes without affecting the cooperative relationship of said labyrinth seal parts.

2. The apparatus of claim 1 wherein said slipjoint connecting means comprises interlocking means connected to the diaphragm means and the inner wall to prevent relative rotative movement between the diaphragm and said inner wall and simultaneously allowing relative radial movement therebetween.

3. The apparatus of claim 1 wherein said diaphragm means includes an annular shroud connected along its one periphery and supporting at its distal periphery said one part of the labyrinth seal. 

1. In a gas turbine machine having at least one stator vane assembly and one rotor blade assembly, including a rotor disc, disposed within a housing and an inner wall spaced inwardly from the housing to define with the latter an inlet passageway for conducting combustion gases to said stator vane assembly, an improved diaphragm and labyrinth seal assembly comprising: a. a diaphragm means disposed adjacent to the rotor disc of said rotor blade assembly to define with the rotor disc a cooling fluid chamber; b. each vane of stator vane assembly having a root portion; c. a first slipjoint connecting means for connecting said root portions of said stator vanes to the diaphragm means so that relative radial movement is permitted between the stator vanes and diaphragm means due to thermal differential expansion and contraction; d. a source of cooling fluid in communication with the fluid chamber to provide the latter with cooling fluid; e. a labyrinth seal disposed between the diaphragm means and the rotor blade assembly; f. one part of said labyrinth seal being carried by diaphragm means while another part is carried by the rotor blade assembly; and g. a second slipjoint connecting means for connecting the diaphragm means to the inner wall of the inlet passageway so that thermal differential expansion and contraction in a radial direction is permitted between the inner wall and said diaphragm means; h. said first and second slipjoint connecting means coacting to permit relative radial movement between the diaphragm means and said inner wall and stator vanes without affecting the cooperative relationship of said labyrinth seal parts.
 2. The apparatus of claim 1 wherein said slipjoint connecting means comprises interlocking means connected to the diaphragm means and the inner wall to prevent relative rotative movement between the diaphragm and said inner wall and simultaneously allowing relative radial movement therebetween.
 3. The apparatus of claim 1 wherein said diaphragm means includes an annular shroud connected along its one periphery and supporting at its distal periphery said one part of the labyrinth seal. 